The invention relates to a device and method for monitoring a power semiconductor switch to ensure the functional safety of the respective power semiconductor.
The invention addresses the problem that, for an item of equipment incorporating a switching element, a means of testing whether the switching element is available must exist if the equipment is to meet a heightened safety level. The same applies if a power semiconductor switch is to be used as the switching element. Accordingly, in the case of an item of equipment having a power semiconductor switch as the switching element, e.g. a power converter, it is necessary to be able to test the operation of the power semiconductor switch regularly in order to ensure that it is available.
There is currently no known device and method for such monitoring of a power semiconductor switch. Hitherto, mechanical relays have mainly been used for safety-relevant tasks. An additional mechanical contact unit in such a relay enables the relay to be monitored for correct operation. If power semiconductor switches are used for safety functions, it has hitherto only been possible to provide monitoring of the power semiconductor switch for operability by means of “trial operation”. However, this involves the power circuit containing the power semiconductor switch and is therefore somewhat undesirable.